Picture producing devices



, April 28," 1959 B. VKAZAN PICTURE PRODUCING nsvzcss Filed Jan. 15,1956 1 INVENTOR. BENJHMIN United States 2,884,566 PICTURE PRODUCINGDEVICES Princeton, N.J., assignor to Radio Cor- Benjamin Kazan,

a corporation of Delaware This invention relates to mural type pictureproducing devices, and it has for its object to provide a novel andimproved device of this type for producing a large area flat televisionpicture without the use of optical projection equipment or cathode raytubes.

Another object of the invention is to provide a mural type televisionpicture scanning device comprising an array of parallel light-emittingstrips and a second array of parallel light-gate strips arranged atright-angles thereto, which requires only two lead wires for each striprather than for each picture element as heretofore, thus not onlyeffecting important economies in construction and assembly but alsoeliminating the possibility of electrostatic coupling between wires andconsequent distortion of the picture.

Various other objects and advantages will be apparent as the nature ofthe invention is more fully disclosed.

In the prior art, picture scanning devices of the above type require atleast one wire lead to each element of the picture. This type ofconstruction is difficult to make where the picture comprises a largenumber of elements.

Another type of prior art device employs separate arrays of horizontaland vertical conductors between which picture elements are defined. Apicture element is energized by the application of voltages to aselected horizontal and a selected vertical conductor. However, theleads to the individual horizontal and vertical conductors areelectrically connected and the applied voltages appear on conductorsother than the intended ones. Poor picture contrast and high dissipationof input energy result in such devices.

According to the present invention, separate horizontal and verticalelements or strips are provided which are electrically isolated fromeach other and only two wires are required for each horizontal andvertical strip rather than for each picture element. One set of strips,either the horizontal or vertical, comprises the light producing portionof the device, and the other set of strips constitutes, in eiiect, gatesfor controlling the amount or" light emitted by the said lightproducers.

The separate horizontal and vertical strips may be variouslyconstituted, as hereinafter more fully described. In a preferredembodiment disclosed herein for purposes of illustration, the lightproducing elements are the vertical strips and are shown aselectroluminescent cells which include a layer of electroluminescentphosphor material between a pair of conductive strips at least one ofwhich is transparent. The horizontal gate members as shown herein may beeither Donal type liquid suspension valves or they may be composed ofstrips of electrooptical material such as zinc sulfide. In the Donaltype gate a liquid cell carrying a multiplicity of flat conductiveplatelets is oriented between a pair of conductive transparent plates.When a field is applied between the plates, the conductive platelets arelined up to allow light to pass through with the degree of alignment andthe amount of light passed being proportional to the applied field.Similarly, the light output from the electrolumiatent O nescent cellsdepends on the field applied between the conductive strips.

In the operation of the device of the present invention, one lead toeach electroluminescent cell is grounded and the other is connected to acommutator. Each of the gates has one lead grounded and the otherconnected to another commutator. A signal modulated voltage source isalso coupled to one of the sets of strips. The commutator connected tothe vertical strips is operated at picture horizontal scanningfrequency, and the com mutator connected to the horizontal strips isoperated at typical vertical switching frequency. Thus during the timewhen any one horizontal element is energized, the vertical elements areenergized successively so that individual picture elements produce alight output which depends in intensity on the signal applied at thatinstant from the modulated signal source.

Another embodiment of the invention includes a large area steady lightsource which is not modulated and separate arrays of horizontal andvertical light gates or valves disposed in front of the light source.With the proper switching operation as described above, and theapplication of video signals to one of the arrays, the light passed as aresult of the cooperative action of the arrays of gates is in the formof a visible picture.

The invention is described more in detail in connection with theaccompanying single sheet of drawings, in which:

Fig. l is a diagrammatic perspective view of a mural type pictureproducing device embodying the present invention;

Fi 2 is a similar view illustrating a first modification of theinvention; and,

Fig. 3 is a similar View illustrating a second modification of theinvention.

The mural type picture producing device illustrated in Fig. 1 comprisesa multiplicity of substantially coplanar vertical light-emitting stripsA mounted in back of a multiplicity of co-planar horizontal light gatestrips B. The said strips are all electrically isolated from each other.The strips or elements A and B are preferably of small width and thestrips A are closely spaced and the strips 13 are closely spaced so thatthe area defined by any two crossed A and B strips is of the order ofthe desired area of a picture element.

The vertical light-emitting strips A comprise electroluminescent cellsconsisting of a layer 10 of electroluminescent phosphor material betweena pair of conductive strips 12 and 14, with at least the strips 14 whichare closest to the gates B, being transparent. The phosphor material maybe copper activated zinc sulfide in a suitable transparent plasticbinder such as ethylcellulose. The conductive strips may be of tinoxide, tin chloride, gold, or the like deposited on glass plates (notshown). Electroluminescent cells emit light when an alternating electricfield is applied across them. The light-emitting strips mayalternatively consist of an array of parallel gas discharge tubesproducing light either from the gas discharge directly or with the aidof phosphor in the gas tubes as used in fluorescent tubes. A furtheralternative arrangement would consist of parallel tungsten filamentWires for producing the light.

The horizontal light gate strips B may each consist of a layer ofelectro-optical material 16, such as zinc sulfide, sandwiched betweentransparent conducting electrodes 18 and 20, which may be of the sametype as the strips 12 and 14, and a pair of light polarizing filters 22and 24 which are out of phase. Without the polarizing eftect of the zincsulfide layer, light transmitted through the filter 22 would not passthrough the filter 24. However, the zinc sulfide has the property ofrotating the plane of polarization of polarized light passing throughPatented Apr. 28, 1959' it when an electric field is applied across itin the direction of the light transmission. The degree of polarizationdue to the zinc sulfide is proportional to the magnitude of the electricfield. Thus, light passes through the filter 24 in an amount dependingon the electric field across the zinc sulfide layer.

An alternative form of light gate strip consists of an elongated cellcontaining a liquid suspension of platelike particles as described by J.S. Donal and D. B. Langmuir in Proc. 1. R. E., 31, pp. 208-213, 1943.Still another form of light gate strip consists of elongated Kerr cellssandwiched between polarizing filters and with a field applied in adirection perpendicular to that of the light transmission.

In one operative arrangement as illustrated in Fig. l, a lead 26 isconnected to each conductive strip 14 of each light-emitting strip A andto a source of reference poten tial such as ground. A lead 28 isconnected to each conductive strip 12, to a commutator 30 and to oneterminal of a signal modulated voltage source the other terminal ofwhich is grounded. The modulating signal may be a video signal or thelike. Each of the light gates. B has one lead 34 from the conductiveelectrode 20 to ground and another lead 36 from the conductive electrode18 to a commutator 38 and to a suitable voltage source such as a battery40.

The commutator 30 is operated at picture horizontal scanning frequency,and the commutator 38 is operated at the required vertical switchingfrequency. In opera tion, one of the light gate strips B is made lighttransmitting for the scanning time of one horizontal line (all otherlight gate strips B held at cut-oft). During this time, each of thelight-emitting strips A is sequentially switched on and caused to emitlight instantaneously. In this manner one line of picture information isreproduced. By switching open the next gate strip B a new line ofpicture information can be presented by again sequentially switching onthe light-emitting strips A. Since the light intensity of any pictureelement may be controlled by either the instantaneous power applied tothe light-emitting strips A or to the light gate strips B (determiningthe degree to which the light gate strip is made light transmitting atany instant) the video signal may be applied to either set of stripssimultaneously with the switching power to produce a half-tone picture.The scanning described above may also be accomplished by applying powerto a single light-emitting strip for a line time and during this periodsequentially switching open the light gate strips.

Fig. 2 illustrates a modification of the invention in which thelight-emitting means comprises a single panel 42 of electroluminescentphosphor on a single conductive plate 44 with separate transparentconductive strips 46 on the free surface of the phosphor layer. In thisembodirnent of the invention, the plate 44 is grounded by a lead 48while the conducting strips 46 are connected to the commutator 30 byleads 50 and to the signal modulated source 32. The light gate stripsmay be constructed, and connected to commutator 38 and battery 40 in themanner previously described in connection with Fig. 1.

Fig. 3 illustrates a modification of the invention in which thelight-emitting means is a single large-area panel 52 which emits lightthrough at least one large-area surface. The panel 52 is a steady lightsource and may be of the incandescent type or any other suitable type.Horizontal and vertical arrays of light gate strips B and B,respectively, are disposed in front of the light-emitting surface of thepanel 52 and these may be of the type described above and shown as B inFig. 1. The portions of the light-emitting surface which are not maskedby the strips B and B" are provided with an opaque coating 54 of blackpaint or the like or are otherwise masked to prevent spurious lightemission from the device.

In this embodiment of the invention, the visible image is produced inessentially the same way as in Fig. 1 with the light transmission fromeach picture element being determined by the switching and interactionof the light gate strips due to the voltages applied thereto.

What is claimed is:

1. Mural type picture producing apparatus comprising means including agroup of elongated parallel substantially co-planar electricallyenergizable members for producing a bar of light extending along eachmember, a group of elongated parallel substantially co-planarelectrically controllable light gate members each extending transverselyacross said members and defining therewith a multiplicity of pictureelements, and circuit means for selectively energizing a particular oneof said members throughout its length and simultaneously opening aparticular one of said light gate members throughout its length.

2. Mural type picture producing apparatus comprising two superimposedgroups of parallel elongated electrically isolated members having themembers of one group arranged perpendicular to those of the other groupand defining a multiplicity of picture elements at the points where saidmembers cross, the members of one group being light-emissive throughouttheir length and the members of the other group constituting elongatedgates controlling the passage of light from said light-emissive members,means including a switching device having a single circuit connectionwith each of said light-emissive members for sequentially activatingsaid light-emissive members, and means including a signal source and asecond switching device having a single circuit connection with each ofsaid gate members for sequentially opening said gate members.

3. A mural type picture producing device according to claim 2, in whicheach of said light-emissive members comprises a layer ofelectroluminescent material between a pair of conductive strips at leastone of which is transparent, and in which each of said light-emissivemembers has one conductive strip grounded and the other conductive stripconnected by a single lead to said firstmentioned switching device.

4. A mural type picture producing device comprising, in combination, afirst group of closely spaced parallel electrically conductive stripmembers extending in a first direction, a second group of closely spacedparallel electrically conductive strip members spaced from the stripmembers of said first group and extending in a direction having at leasta component normal to said first direction, electrically energizablelight-emitting means cooperating individually with each of the stripmembers of one of said groups to produce bars of light along said stripmembers, electrically controllable light valve means cooperatingindividually with each of the strip members of the other of said groups,and means including a cornmutator for selectively energizing anindividual stri member of one of said groups simultaneously with anindividual strip member of the other of said groups.

5. A mural type picture producing device according to claim 4, in whichsaid strip members of said first group are perpendicular to said stripmembers of said second group.

6. A mural type picture producing device comprising, in combination, afirst series of pairs of electrically conductive elongated stripmembers, at least one of said strip members being optically transparent,elongated electrically energizable light-emitting means sandwichedbetween the strip members of each pair, a second series of pairs ofelectrically conductive elongated strip members all formed of opticallytransparent material and extending transversely of said first series ofpairs of strip members adjacent to said optically transparent onesthereof, and elongated electrically controllable light valve meanssandwiched between the strip members of said second pair forindividually controlling the transmitted light emitted from apredetermined longitudinal portion of a plurality of said light-emittingmeans.

7. A mural type picture producing device comprising,

in combination, electrically energizable light-emitting means, a seriesof elongated transparent electrically conductive strip members extendingacross said light-emitting means for selectively causing the emission oflight individually from an elongated portion thereof adjacent to one ofsaid strip members, a series of pairs of elongated transparentelectrically conductive strip members extending transversely of saidfirst-named series of strip members, and a plurality of elongatedelectrically controllable light valve means each individually sandwichedbetween one of said pairs of strip members.

8. A mural type picture producing device comprising means including agroup of elongated parallel substantially co-planar electricallyenergizable members for producing a bar of light extending along eachmember, and a group of elonga.cd parallel substantially co-planarelectrically controllable light gate members each extending transverselyacross said members and defining therewith a multiplicity of pictureelements.

9. A mural type picture producing apparatus comprising a large arealight-emitting panel, a first group of elongated parallel substantiallyco-planar electrically controllable light gate members in front of andspaced from said panel, and a second group of elongated parallelsubstantially co-planar electrically controllable light gate memberseach extending transversely across said first light gate members anddefining therewith a multiplicity of picture elements.

References Cited in the file of this patent UNITED STATES PATENTS1,754,491 Wald Apr. 15, 1930 1,779,748 Nicolson Oct. 28, 1930 2,698,915Piper Jan. 4, 1955 2,749,480 Ruderfer June 5, 1956

